Electronic transducer tube



G. L, KRlE GER ELECTRONIC TRANSDUCER TUBE Filed Nov. 50, 1950 INVENTOR GARDNER L. KRIEEER ATTORNEY Patented Jan. 12, 1954 ELECTRONIC TRANSDUCER TUBE Gardner L. Krieger, Princeton, N. J., assignor to Radio Corporation of America, a corporation of Delaware Application November 30, 1950, Serial No. 198,367

8 Claims. '1

The present invention relates to electron dis charge devices for translating mechanical energy into electrical energy, and more particularly to an electronic transducer tube suitable for reproducing sound recorded both laterally and vertically in the same sound groove of a phonograph record.

Heretofore in the art of sound reproducing, electronic transducer tubes commonly in use comprised an evacuated vessel having two or more electrodes therein one of which, such as the anode or grid, was arranged to be movable relative to the others. Means were provided for vibrating the movable electrode in order to vary the length of the electron path between the electrodes and thereby to produce corresponding electrical signals in the output circuit of the tube. The means which has been used for vibrating the movable electrode has been, for example, the reproducing stylus of a phonograph pick-up. The application of tubes of this type has, however, been limited to trans ating vibratory movements in one particular direction or plane.

In cases where two channel recording is found useful, for example, in stereophonic sound reproduction, where sound is recorded both laterally and vertically in the same sound groove for reproduction simultaneously, the above-mentioned transducer tubes are not found suitable.

It is a primary object of the present invention, therefore, to provide an electronic transducer tube suitable for translating mechanical vibrations in different directions into corresponding electrical signals.

It is also an object of the present invention to provide an electronic transducer tube suitable for picking up and simultaneously translating sound recorded laterally and vertically in the same sound groove of a phonograph record.

It is another object of the present invention to provide an electronic transducer tube which is suitable for picking up and translating separately as well as simultaneously sound recorded both laterally and vertically in the same sound groove of a phonograph record.

It is a further object of the present invention to provide an electron discharge device suitable for translating mechanical vibrations set up in dilierent directions or planes into separate electrical variations corresponding to movements in the diiferent directions using but a single vibra tory member for picking up the different movements.

A still furtherobject of the present invent on is to provide an electronic transducer tube which is suitable for use in phonograph pick-ups, vibration analyzing equipment, or other similar devices in which it is desired to simultaneously translate movements in more than one direction or plane.

An additional object of the present invention is to provide an electron discharge device which can be manufactured easily and which is very efficient for the purposes for which it may be applied.

In accordance with the present invention, the electronic transducer tube comprises an. evacuated vessel having a flexible diaphragm as part of its wall structure and a plurality of electrodes mounted therein. One of the electrodes is mounted for movement with respect to two other fixed electrodes. The fixed electrodes are also disposed substantially degrees apart in relation to the movable electrode so that they will be operative to translate vibratory movements imparted to the movable electrode which originate in planes normal to each other.

The novel features characteristic of the resent invention, as well as additional objects and ad vantages thereof, will be understood better from the following detailed description when read in connection with the accompanying drawing in which,

Figure 1 is a side View, in section, of an electronic transducer tube in accordance with a preferred embodiment of the present invention, Figure 2 is a sectional view of the transducer tube shown in Figure 1, taken along the line 2--2, and

Figure 3 is a wiring diagram showing how the transducer tube can be utilized in an audio reproducing system.

Referring more particularly to the drawing wherein similar reference characters designate corresponding parts throughout, the electron discharge device of the present invention is shown in the form of an electronic transducer tube i. The transducer tube l comprises an evacuated, metallic vessel or shell 3 having an opening in the wall structure which is closed by a thin, fiexible, metallic diaphragm 5. In the particular embodiment shown, the shell 3 comprises a relativeiy small, cylindrical, evacuated envelope with the diaphragm closing one end thereof.

Two electron emitting cathode electrodes '5', 9, which may be heated separately by filaments Ii, are mounted in fixed positions within the shell 3 in proximity to the walls thereof. An anode o1 control-electrode I3, which is constituted by the portion of an elongated rod or bar i5 disposed within the shell, extends through and is secured intermediate its ends to the diaphragm 5. The control electrode [3 is mounted to normally extend in a direction parallel to and spaced uniformly from each of the cathode electrodes 1, 9 alon the longitudinal axis of the cylindrical shell 3. The fixed cathode electrodes 1, 9 are also arranged. substantially 99 degrees from each other in relation to the control electrode l3 as a center or in relation to the longitudinal axis of the shell 3. Thus, the control electrode I3 is suspended within the shell and is freely movable relative to each of the cathode electrodes 1, 9 upon application of a force thereto externally of the shell. The force for effectingmovement of the control electrode 13 may be applied by any suitable means connected to the control electrode. For example, as shown in Figure l, the

outwardly extending end I? of the rod l5, which is external to the shell 3, is attached by a yoke 19 and a stylus arm 26 to a reproducing stylus 23 suitable for use in translating sound recorded in a sound groove of a phonograph record (not shown). The yoke 1e, arm 2! and stylus 23 are so oriented that they will cause the control electrode 3 to move toward or away from the fixed electrodes l, 9 according to the direction of the force applied to the stylus by the sound groove on the record. If the sound groove is of the vertical or hill-and-dale type, the control electrode I3 will move toward and away from the fixed cathode electrode 9 disposed above it. However, if the sound groove is of the lateral type, the control electrode i? will move toward and away from the other fixed cathode electrode 1. cases where movement is imparted to the control electrode it by forces normal to eachother,

the resultant movement will be in some plane intermediate the planes including the fixed electrodes l, 9 and the common control electrode. Thus, it will be recognized that if the sound groove has both lateral and vertical components, the present invention makes it possible to reproduce both components simultaneously through separate channels with the one transducer. Suitable application may be found for such a tube in other similar circumstances where it is desired to analyze vibratory motion or forces originating in planes normal to each other.

Although various ways of connecting the electronic transducer tube of the present invention to a utilization circuit may be provided, one form is illustrated by an electrical circuit diagram in Figure 3 of the'drawing. The transducer tube- 25 represented therein comprises a movable anode 2"! and two fixed cathodes 29, 3| within an evac uated envelope 33. Load resistors 35,. 31 are con nected, respectively, between each of the oathodes 29, 3| and a point of fixed reference potential 39. A source of energizing potential is provided by any suitable means, such as a battery 4! and is connected between the anode 21 and the point of fixed reference potential 39. The outputs of the respective tube sections are selectively connected to an audio amplifier 43' of any suitable kind through a switching mechanism 45 and a blocking capacitor 41. The output of the audio amplifier is connected to a loudspeaker 49, or any other suitable reproducer.

The system illustrated in Figure 3 will be found to operate in the following manner: upon movementof the anode 2! relative to each cathode 29, 33 the current fiow through each section of. the tube will vary inversely as the distance of separation between the anode and each cathode.

The varying current thus produced will cause a varying voltage to be developed across the load resistor 35, 31. This varying voltage is then applied to the input of the audio amplifier 43 by means of the switching mechanism 45 and the blocking capacitor 41, the latter being of such a magnitude as to be conductive at the desired frequency. The applied input voltage is then amplified by the audio amplifier, in a manner well known in the art, to provide sufilcient power to operate the loudspeaker 49, or other suitable device, for reproducing recorded signals or vibrations picked up by the transducer tube.

Fromthe foregoing description, it is apparent that the electronic transducer tube is an extremely simple device which is particularly adapted'for translating vibratory movements or forces in two separate directions. It will be found to be particularly useful in sound reproduction from a phonograph re'cord, especially in those cases where sound is recorded both vertically and horizontally in the same sound groove. The tube of the present invention not only permits simultaneous reproduction of sound recorded vertically and laterally in the same sound groove but also obviates the need for separate presently available pick-ups for the same purpose.

Although there is illustrated and described but a single embodiment of the present invention, it will be recognized by persons skilled in the art that various modifications and changes are possible within the spirit of the invention. For example, the movable anode may be adapted for connection to other apparatus for analyzing vibratory forces in different directions, or the various tube elements may be altered in design to provide a more eificient apparatus. Therefore, it is desired that the particular form of the present invention described herein shall be considered as illustrative and not as limiting.

What is claimed is:

1. An electron discharge device comprising an evacuated vessel having a flexible diaphragm as part of its wall structure, a first electrode mounted in fixed position within said vessel and adapted to emit electrons, a second electrode mounted in fixed position, parallel to and spaced from said first electrode within said vessel and adapted to emit electrons, a third electrode secured to said diaphragm extending inwardly of said vessel generally in a direction parallel to and spaced from both said first and second electrodes, said first and second electrodes being disposed equal distances from said third electrode and su stantially from each other in relation to said third electrode as a center, said third electrode being movable toward and away from both said first and second electrodes, and means connected to said third electrode extending externally of said vessel for imparting movement to said third electrode.

2. An electron discharge'device according to claim 1 wherein said third electrode extends through said diaphragm and wherein said means for imparting movement to said third electrode is coupled to the portion of said third electrode which is external to said vessel.

3. An electron discharge device according to claim 2 wherein said. means for imparting movement to said third electrode comprises a reproducing stylus and means connecting said stylus to said external portion of said third electrode.

4. An electronic transducer tube comprising a cylindrical, evacuated envelope having a flexible diaphragm closing one end thereof, two electron emitting cathodes disposed in proximity to said envelope, said cathodes being disposed 90 apart in relation to the longitudinal axis of said envelope, and an anode disposed along said longitudinal axis within said envelope, said anode being secured to said diaphragm and being movable relative to each of said cathodes.

5. The invention as defined in claim 4 wherein said anode extends through said diaphragm and characterized by the addition of means attached to the portion of said anode which is external to said envelope for imparting vibrations thereto upon application of forces to said means.

6. The invention as defined in claim 5 wherein said means includes a phonograph needle adapted to cooperate with a phonograph record.

'7. A low mass, light weight transducer unit for use in electronic phonograph pickups and the like, comprising a relatively small electronic tube shell having an opening in the wall structure thereof, a thin flexible diaphragm providing closure means sealing said opening, two fixed cathode electrodes disposed within said shell, a control electrode attached to said diaphragm at least a portion of which extends into said shell in spaced relation to each of said cathode electrodes, said cathode electrodes being disposed in parallel, spaced apart relation and 90 apart in relation to said control electrode, means connected with said control electrode for imparting movement thereto with respect to said cathode electrodes in response to a force applied thereto externally of said shell, and means providing electrical connections with said fixed electrodes and said control electrode externally of said shell.

8. An electronic transducer tube comprising an evacuated envelope having a flexible diaphragm closing one end thereof, a plurality of electron emitting cathodes supported from and enclosed by said envelope, an anode enclosed by said envelope, said anode being secured to said diaphragm and being movable relative to each of said cathodes, one of said cathodes and said anode lying in one plane, and another of said cathodes and said anode lying in a different plane.

GARDNER L. KRIEGER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,482,972 Gordon Sept. 27, 1949 2,491,390 Olson Dec. 13, 1949 2,491,391 Rose, Jr. Dec. 13, 1949 2,506,589 Hall May 9, 1950 

